What pharmacologic agents are recommended for mood stabilization in an adult with borderline personality disorder who has marked mood swings?

Pharmacotherapy for Mood Stabilization in Borderline Personality Disorder

For adults with borderline personality disorder experiencing marked mood swings, pharmacotherapy is NOT recommended for the mood instability itself—psychotherapy (dialectical behavior therapy or psychodynamic therapy) is the treatment of choice. 1, 2

Critical Distinction: BPD Mood Swings vs. Comorbid Mood Disorders

The first and most important step is determining whether the mood swings represent:

• Emotional dysregulation intrinsic to BPD (rapid shifts within hours, triggered by interpersonal events) → No medication indicated 1
• A discrete comorbid major depressive episode (persistent low mood ≥2 weeks meeting full DSM criteria) → SSRI indicated 1

Antidepressants should NOT be used for transient depressive or anxious moods that are part of BPD's core emotional dysregulation, as recommended by WHO guidelines. 1 This is a common pitfall—prescribing SSRIs for the affective instability of BPD itself lacks evidence and may lead to unnecessary polypharmacy. 3, 2

When Pharmacotherapy IS Appropriate

For Comorbid Major Depressive Episode

If the patient meets full criteria for a separate major depressive episode (not just mood swings):

• Initiate sertraline 50 mg daily OR escitalopram 10 mg daily as first-line treatment 1
• Continue for 6–12 weeks before judging the trial unsuccessful 1
• If inadequate response, escalate dose, switch to another SSRI, or try bupropion following standard depression algorithms 1

The evidence supporting SSRIs specifically for BPD core symptoms is weak 4, but when a discrete comorbid major depression is diagnosed, standard antidepressant treatment is appropriate. 1, 2

Medications That May Help Specific Symptoms (Not Mood Swings Per Se)

While no medication treats BPD mood instability directly, some agents show benefit for other core symptoms:

• Mood stabilizers (topiramate, lamotrigine, valproate) and second-generation antipsychotics (aripiprazole, olanzapine) have shown effectiveness for impulsivity, anger, and associated psychopathology—but NOT for overall BPD severity 4
• These should target specific symptoms, not be used as "mood stabilizers" for BPD mood swings 4

What to Avoid

Never prescribe benzodiazepines (diazepam, lorazepam) in BPD due to heightened risk of dependence, disinhibition, and worsening impulsivity. 1, 2 This is an international guideline consensus. 1

Acute Crisis Management Only

For short-term stabilization of acute crises (suicidal ideation, severe agitation):

• Low-potency antipsychotics (quetiapine) or sedating antihistamines (promethazine) may be used temporarily 2
• These are NOT for maintenance treatment of mood swings 2
• Preferred over benzodiazepines 2

Treatment Algorithm

1. Assess: Does the patient have a discrete comorbid major depressive episode (≥2 weeks, meets full DSM criteria)?

   • Yes → Start sertraline 50 mg or escitalopram 10 mg daily 1
   • No (mood swings are part of BPD emotional dysregulation) → No medication; refer for DBT or psychodynamic therapy 1, 2

2. If treating comorbid depression: Continue SSRI for 6–12 weeks before changing 1

3. Avoid polypharmacy and medications with overdose risk 3

4. Reserve antipsychotics/mood stabilizers for specific target symptoms (impulsivity, anger), not mood swings 4

Key Caveat

Psychotherapy is the primary treatment for BPD—medication should only be adjunctive for discrete comorbid disorders. 1, 2, 5 Dialectical behavior therapy reduces BPD symptom severity with medium effect sizes (standardized mean difference -0.60 to -0.65), while no psychoactive medication consistently improves core BPD symptoms. 2 The most robust evidence shows DBT and mentalization-based therapy are more effective than usual care. 5, 6